Project Summary/Abstract: The goal of this project is to maintain and enhance the specific pathogen free (SPF) pigtail macaque (M. nemestrina) breeding colony at the Washington National Primate Research Center (WaNPRC). This colony is the largest domestic breeding colony of M. nemestrina and the primary source of this important animal model for AIDS studies and other types of biomedical research in the United States. M. nemestrina have unique immunological, genetic, behavioral, anatomical, and physiological characteristics that make them an essential model in a number of areas of research related to HIV/AIDS. Specific pathogens (SIV, SRV, STLV-1, McHV-1) are a threat to animal or human health or interfere with research and must be excluded to optimize nonhuman primate research models. In this proposal, we discuss how we will maintain the WaNPRC SPF M. nemestrina breeding colony to provide animals of the highest quality to meet research needs. We are in the process of consolidating breeding operations at our Arizona breeding facility. Breeding and maintenance of the SPF breeding colony, including financial sustainability, are described in Core 1, Husbandry and Management Core. The viral testing that is performed to ensure that the colony remains SPF is described in Core 2, Viral Testing Core. Genetic management and genotyping animals for parentage and major histocompatibility complex alleles are described in Core 3, MHC Genetic Typing Core. The SPF M. nemestrina colony serves as a national resource, providing animals to AIDS researchers across the country, with priority given to NIH-funded investigators.